#include<iostream>

using namespace std;


int main()
{
	string words = "hello";
	string t;
	t.push_back(words[0]);
	t.push_back(words[1]);
	cout<<t<<endl;
	words[0]='H';
	cout<<'1'-48<<endl;
	printf("ASCII code: %d,value: %c\n",50,50);
	cout<<words<<words.size()<<endl;
	printf("%s",words.c_str());
	string s1;
	cin>>s1;
	if (s1.empty())
		printf("is empty.");
	else
		cout<<s1<<endl;

}
